In 1972, a belt driven tape cartridge design (U.S. Pat. No. 3,692,255, issued to Robert A. Von Behren) was introduced for use in the computer industry for digital tape recording. Cartridges commonly in use in 1972 were approximately 100 mm by 150 mm and the magnetic tape was 6.35 mm (0.250 inches) wide. Cartridges of that size and corresponding drive mechanisms are still commercially available. In 1976, smaller data cartridges were developed, as described by Alan J. Richards, Mini Data Cartridge: A Convincing Alternative for Low-Cost, Removeable Storage, Hewlett-Packard Journal, May, 1976. The mini-cartridge size is 63.5 mm by 82.5 mm. Versions of the mini-cartridge are commercially available from a variety of vendors with tape widths varying from 3.81 mm (0.150 inches) to 6.35 mm (0.250 inches). New versions of mini-cartridges have been proposed having a tape width of 8.00 mm (0.315 inches). The external dimensions of the proposed cartridges are identical to existing mini-cartridges but there are numerous internal changes to accommodate wider tape.
Both sizes of cartridges described above have two openings in one edgewall. The first opening provides access to the tape by a magnetic head. The magnetic head travels across the width of the tape, transverse to the direction of tape movement, accessing one track at a time for reading or writing. The second opening provides access to a driven roller (capstan) inside the cartridge by an external driving roller (puck) in the drive mechanism. The external driving roller (puck) is rotated by a motor in the drive mechanism. In full height drives and half-height drives, the external driving roller (puck) is typically driven directly by the drive motor. As drive height decreases, there may be a mechanical interference between the drive motor and the magnetic head. The interference problem is made even worse with the proposed cartridges having a tape width of 8.00 mm (0.315 inches), increasing the distance the magnetic head has to travel. Therefore, in newer shorter height drives, the drive motor is typically displaced relative to the driving roller (puck) and connected to the driving roller (puck) by a belt or an intermediate roller. For example, see U.S. Pat. No. 5,210,664 issued to Mark W. Perona on May 11, 1993. Belts and intermediate rollers add cost and may slip or cause other speed problems. A direct drive is desirable as the lowest cost and most reliable way of connecting the drive motor to the driving roller (puck). A drive mechanism is needed that has both a directly driven roller (puck) and room for full movement of the magnetic head.